Magnetic data storage devices generally include magnetic recording heads, commonly referred to as transducing heads, which detect and modify the magnetic properties of a magnetic storage medium to store data.
Air-bearing sliders have been used in magnetic disc drives to appropriately position the transducing head above the rotating magnetic disc. During operation, the disc rotates at high speeds, which generates a stream of air flow immediately adjacent to the flat surface of the disc. This stream of air acts upon a lower air-bearing surface of the slider and generates a force directing the slider away from the disc and against a load beam causing the slider to “fly” a small distance above the disc. As magnetic disc storage systems are designed for greater and greater storage capacities, the aerial density of magnetic discs is increasing, requiring that the air-bearing gap between the transducer carried by the slider and the rotating magnetic disc be reduced, which in turn results in operating the air-bearing slider at ultra-low fly heights.
One cause of transducing head and disc collision is heat-induced protrusion of the transducing head toward the disc. Generally speaking, the materials from which transducing head components are made have relatively large coefficients of thermal expansion, and, therefore, are particularly subject to shape changes caused by variations in temperature. During operation, the various layers of the transducing head are heated by, e.g., electrical resistance generated as a result of the operation of the magnetic read and write heads included in the transducing head. Heating the transducing head causes the head to expand, and thereby protrude toward the magnetic disc. In ultra-low fly height applications, even small protrusions of the transducing head can cause head-to-disc collisions.
Recently, magnetic disc storage systems have seized on the heat-induced protrusion of transducing heads as a way to maintain small air-bearing gaps and, simultaneously, increase fly heights. Increasing fly heights has the obvious benefit of reducing the number and/or risk of collision with the magnetic disc. By employing electrical heaters in the transducing head, the amount the head protrudes during operation, and thereby the size of the air-bearing gap can be controlled as a function of the power applied to the heaters to induce protrusion of the transducing head toward the magnetic disc. Because the heat-induced protrusion of the transducing head is controlled to position the head relative to the disc as necessary for optimal performance, the fly height of the slider carrying the head can be increased.